How to Build a PH Test Electronic Tester

Monitor the pH level of your aquarium using an electronic pH tester.

Maintaining pH and carbon dioxide levels in an aquarium can be difficult. Add too much carbon dioxide and you'll stress your fish. Add too little and your plants will suffer. Allow the pH to fluctuate wildly and you risk killing plants and animals alike. For this reason, many aquarium enthusiasts use an electronic pH meter to test the water. You can build a pH test electronic tester using relatively inexpensive and common parts.

Things You'll Need

• pH probe
• 2 batteries, 9 volt
• TL082 Dual JFET-input IC
• Digital voltmeter
• 2 battery harnesses
• BNC panel
• BNC connector
• Soldering iron

Instructions

1. Attach one battery to a battery harness. Attach the second battery to the second harness.

2. Connect the first battery harness to pin 8 of the TL082 using the negative wire. Fuse the connection using the soldering iron.

3. Connect the first battery harness to the BNC panel's grounding latch using the positive wire. Attach the second battery harness's positive wire to the BNC panel's grounding latch to form a triple connection. Fuse this triple connection with the soldering iron.

4. Connect the second battery harness's positive wire to pin 4 on the TL028. Fuse the connection using the soldering iron.

5. Connect the BNC panel to the BNC connector. Screw the pH probe into the BNC connector.

6. Solder the TL082 directly into the BNC connector. Solder pins 6 and 7 of the TL082 together.

7. Connect the digital voltmeter's positive wire to the soldered pins 6 and 7 of the TL082. Solder the connection.

8. Ground the digital voltmeter by connecting its negative wire to the BNC rack. Solder the connection.

Tips & Warnings

• After completing the pH meter, you will need to calibrate it. The probe will produce no volts when the pH of a solution is 7, or neutral. A higher base pH will produce a positive voltage and an acidic pH will produce a negative voltage. Each pH unit is equivalent to 59 millivolts.

• The circuit constructed for the pH meter can produce a high voltage capable of harming users or starting a fire if not properly handled.

• The soldering iron produces intense heat and should be used with care.

References

• 66pacific: Building the Simplest Possible pH Meter

Resources

• 66pacific: A pH Measurement & Control System for the planted aquarium